1. Field of the Invention
The present invention relates in general to the release of volatile substances and, more particularly, to a device for controllably releasing volatile substances in their vapor phase to the surrounding atmosphere.
2. Background Art
Devices for delivering volatile substances from a container, as a liquid, to the atmosphere, as a vapor, have been known in the art for several years. In particular, many of these devices make use of the principle of diffusion. For instance, some devices make use of a wick based system. In these systems, one end of a wick is placed in a fluid to be dispensed, while the other end is exposed to the atmosphere. Capillary action forces liquid through the wick and up to the exposed end, where the liquid evaporates off of the end of the wick and into the surrounding atmosphere.
Other devices make use of a gravity driven mechanism, allowing liquids to diffuse through a membrane under the force of gravity. For instance, Zembrodt, U.S. Pat. No. 4,948,047 shows a container for holding a liquid reservoir which is in contact with a membrane positioned in the bottom of the container. Under the force of gravity, the liquid diffuses through the membrane and volatilizes into the surrounding atmosphere from the exposed surface of the membrane. Likewise, Munteanu, U.S. Pat. No. 4,917,301, discloses a similar container for housing a liquid, with a membrane in the bottom of the container. Gravity again forces the liquid to diffuse through the membrane, from where it then evaporates into the surrounding atmosphere.
Although these and other conventional controlled delivery systems have worked well, they have failed to provide for both the controlled and constant release of fluids over an extended period of time. It is a well known goal in the art to increase the linearity of the release of fluids from delivery devices. Moreover, the prior art devices have traditionally been inefficient as they have failed to deliver substantial portions of the fluid contained in the fluid reservoir, thus losing the remaining fluid when it is discarded. Finally, such devices have failed to provide a means for a user to control the rate of release of fluids to the surrounding atmosphere, a desirable feature as different users enjoy different concentrations of the volatilized substance in the air.